Many implantable devices use feedthrough elements to connect a hermetically enclosed electronic board to an implanted device such as a measuring and/or a stimulating electrode and/or an electromechanical actuator. A feedthrough comprises an electrical connection between a hermtically closed enclosure and the outside surrounded by insulating material, which allows electrical signals to pass between the surroundings and the hermetical enclosure while maintaining the integrity of the hermetic enclosure.
Implantable housings can be made from titanium. In the case of titanium housing, feedthroughs for the entire housing unit may be assembled into one main titanium body. The manufacturing of the titanium body thus requires a large number of welds, often at least one weld for each feedthrough.
Sometimes, each feedthrough is directly brazed onto a titanium body and requires a complex machined titanium part.
Sometimes the housing is made from alumina (aluminum oxide) which is a ceramic. Such a housing may have feedthroughs all around the outer perimeter of the ceramic. One of the technical difficulties with this design is the machining of very small holes (e.g., 0.4 mm diameter) all around the diameter of ceramic housing, which is made from a very hard material. Another issue is the cost of machining such small and precise holes, which have to be ground with diamond tools.